I don’t think this is do-able. I always thought it could be done, but as usual, as time goes by I figure out that, one by one, all my early ideas were wrong.
If you look around you’ll see that MC’s come in different bore sizes. Some have straight bores, and some MC specs provide 2 different bore sizes. I’m talking about MC’s marketed as OEM replacement, not an effort to use wrong MC’s that happen to fit our car. In fact, if you carefully go thru RealOEM, you’ll see MC’s with different bore sizes in the various years and models.
This idea of different MC bore sizes was long understood to be a rear bore and a front bore. It followed that one could direct more pressure to the rear brakes by selecting an MC with a smaller rear bore.
I had totally bought into this. Over the years I’d tried different MCs trying to feel out a relationship between MC bore size, biasing, and stopping distances.
But this morning I figured out that it might be all wrong. The 2 different bore size measurements are apparently not front and rear, but an MC design that quickfills the caliper to get the pad up against the piston, then the MC’s smaller bore takes over and applies the calibrated pressure.
Google master cylinder step bore. Here’s one such http://www.freeasestudyguides.com/brakes-quick-take-up-master-cylinder.html